ELISA is a straightforward research tool for quantifying analytes in solution. The analytes measured are proteins, such as cytokines, chemokines, immunoglobulins, hormones, or other biomarkers. Typical samples are cell supernatants, plasma, serum, and other bodily fluids. The uncomplicated detection procedure and the versatility of sample choice strengthen the broad use of ELISAs across research fields and diagnostics.